1. Technical Field
The present invention relates to a liquid jet head and a liquid jet apparatus that jet liquid droplets on a recording medium and perform recording.
2. Related Art
In recent years, ink jet-system liquid jet heads that eject ink droplets on a recording paper or the like to record characters and figures, or eject a liquid material on a surface of an element substrate to form a functional thin film are used. This system introduces a liquid, such as an ink, or the liquid material from a liquid tank to a channel through a supply tube, and applies a pressure to the liquid, which is filled in the channel, to eject the liquid through a nozzle that communicates with the channel, as liquid droplets. When ejecting the liquid droplets, the system moves a liquid jet head or a recording medium, and records the characters and figures or forms a functional thin film having a predetermined shape.
JP 7-178903 A describes an edge shoot-type liquid jet head 100 in which a large number of grooves is formed as channels for ejecting a liquid on a piezoelectric body substrate, and which ejects liquid droplets from end portions of the grooves. FIGS. 9A and 9B are cross-section schematic views of a liquid jet head described in JP 7-178903 A. FIG. 9A is a cross-section schematic view of the liquid jet head 100 in a direction perpendicular to a longitudinal direction of the grooves and FIG. 9B is a cross-section schematic view of an ink chamber 103 in a groove direction. The liquid jet head 100 includes a piezoelectric ceramic plate 102, a cover plate 110 bonded on an upper surface of the piezoelectric ceramic plate 102, and a nozzle plate 114 bonded on a side surface of the piezoelectric ceramic plate 102. On the piezoelectric ceramic plate 102, grooves 119 that configure the ink chambers 103 and grooves 104 in which no liquid is filled are alternately arranged sandwiching partitions 106. The cover plate 110 adheres to the upper surface of the piezoelectric ceramic plate 102 through an epoxy-based resin 120. A manifold 121 is formed on the cover plate 110, and is configured to communicate with end portions of the grooves 119 to enable liquid (ink) supply. The piezoelectric ceramic plate 102 uses a PZT ceramic plate, and is polarized into a polarization direction 105.
The grooves 104 are cut and formed to penetrate the cover plate 110 to the piezoelectric ceramic plate 102. A metal electrode 108 is formed on a side surface of the partition 106 that partitions the groove 119 and the groove 104, the side surface being at a side of the ink chamber 103, and an electrode 117 is formed on a side surface of the groove 104 of the partition 106. The metal electrode 108 is formed at an upper portion than the half of the depth of the groove 119, and is pulled out to a shallow groove 107 on a side of one end surface 115 at an opposite side to the nozzle plate 114 of the piezoelectric ceramic plate 102, as a metal electrode 109. The electrode 117 is formed on an inner-side surface and a bottom surface of the groove 104 and a flat portion 116 of the cover plate 110. The electrode 117 is set to a common electric potential, and a drive signal is provided to the metal electrode 109, so that a pressure wave is caused in the liquid filled in the ink chamber 103, and the liquid droplets are ejected through a nozzle 112.
In the liquid jet head 100 described in JP 7-178903 A, the metal electrode 109 is installed on the upper surface at the side of the one end surface 115, which is at the opposite side to the nozzle plate 114 of the piezoelectric ceramic plate 102. Each metal electrode 109 is electrically connected to each metal electrode 108 formed on the side surface of the ink chamber 103. That is, the same number of the metal electrodes 109 are formed as the number of the ink chambers 103. Therefore, if an arraying pitch of the ink chambers 103 becomes narrow, an arraying pitch of the metal electrodes 109 becomes narrow, and patterning of the metal electrodes 109 becomes micronized. Therefore, electrical connection between the micronized metal electrode 109, and wiring for supplying the drive signal from an outside, for example, wiring of a flexible circuit board, becomes difficult. Further, the groove 104 is cut and formed from the cover plate 110 side using a diamond blade. The length of the groove 104 in the groove direction is made shorter than the length of the groove 119 in the groove direction so that the diamond blade does not reach the manifold 121 when the groove 104 is formed. Therefore, the length of the piezoelectric ceramic plate 102 in the groove direction becomes long in order to secure an effective length of a drive wall.